In recent years, with an increase of integration of semiconductor chips, there has been a demand for efficiently dissipating the heat generated in semiconductor chips to the outside. For this purpose, a wiring substrate including a heat sink is proposed as a wiring substrate for mounting a semiconductor chip thereon.
For example, Japanese Laid-Open Patent Publication No. 64-047058 discloses a wiring substrate including a heat sink. When the wiring substrate is produced, an insert molding is performed with a heat sink and a lead frame (outer connection terminal) by using a dielectric resin. In the wiring substrate, an inner circuit pattern part (inner connection terminal) is formed on the dielectric resin so that the inner circuit pattern part is electrically connected to a semiconductor chip.
Moreover, Japanese Laid-Open Patent Publication No. 2007-266172 discloses a wiring substrate in which a metal body (heat sink) and an insulation base of a dielectric resin are bonded. In the wiring substrate, an inner connection terminal is formed on one surface of the insulation base, and the inner connection terminal is electrically connected to a semiconductor chip. An outer connection terminal is formed on the other surface of the insulation base. The wiring substrate is arranged so that the inner connection terminal and the outer connection terminal are electrically connected together by a penetration conductor which penetrates the insulation base.
However, in the wiring substrates according to the related art, the inner connection terminal and the outer connection terminal are formed separately, and then the inner connection terminal and the outer connection terminal are connected together. Hence, there has been a problem that the wiring substrates according to the related art have a complicated structure and a complicated manufacturing method.
Moreover, in the wiring substrates according to the related art, the inner connection terminal and the outer connection terminal are formed on the dielectric resin. In order to improve the reliability against a short circuit, it is necessary that only the required portion of the inner connection terminal or the outer connection terminal are exposed, and a solder resist layer which covers the other portion of each terminal is formed. Hence, there has been a problem that the wiring substrates according to the related art have a complicated structure and a complicated manufacturing method.